nohup

nohup

The nohup command in Unix and Linux stands for "no hang up." It is used to run a command immune to hangups, and it keeps running even after you log out or close the terminal.

Basic Usage

The basic syntax for using nohup is:

nohup command [arguments] &

• command: The command you want to run.

• [arguments]: Optional arguments passed to the command.

• &: Runs the command in the background.

Example

Here’s a simple example of using nohup:

nohup python myscript.py &

• This command starts running the Python script myscript.py in the background, and it continues running even if you log out of the current session.

Output

By default, nohup redirects standard output (stdout) to a file called nohup.out in the current directory and standard error (stderr) to the same file. This allows you to check the output later.

Practical Use Cases

• Long-Running Processes: Use nohup to run processes that take a long time to complete, such as data processing tasks or server processes.

• Remote Sessions: When connected to a remote server via SSH, nohup ensures that processes continue running even if the SSH session disconnects.

Caution

• Output Management: Monitor nohup.out for any error messages or output that might be useful for troubleshooting.

• Process Control: You won't be able to interact with a background process directly unless you've captured its PID for management.

Summary

nohup is a useful command for running processes that need to persist even after logging out or closing the terminal session. It ensures that processes continue running in the background and are not terminated due to hangups or disconnects. Understanding how to use nohup effectively can enhance productivity in managing long-running tasks on Unix and Linux systems.

help